1. Field of the Invention
This invention relates to an inorganic material which comprises water glass and metakaolin, or water glass, metakaolin and a hydrous magnesium silicate type clay mineral, which has good workability and excellent water and hot water resistances when solidified, and also relates to a process for producing same and a solidifying method thereof.
2. Description of the Prior Art
One of materials enjoying wide ranges of industrial applications is water glass. In general, water glass is a colorless, highly viscous, concentrated aqueous solution of an alkali salt of silicic acid obtained by melting silicon dioxide and an alkali. When said water glass is left in air, the water content evaporates and it solidifies. Thus, by utilizing such properties, water glass is widely employed as adhesives for artificial stone, pottery, boxboard, etc., also as coating materials, soil improvers, molding materials, etc.
However, said water glass, even when once solidified, again absorbs water upon contact with water and returns to a viscous liquid. Therefore, it is impossible to use said water glass in highly humid places such as the outdoors, or where it is directly contacted with water. In other words, the solidified product of said water glass has a disadvantage that it has no water resistance.
Heretofore, many attempts have been made to impart water resistance to the solidified product of said water glass and one of these methods is to add a phosphoric acid based hardening agent of heat condensation type, or cement, or zinc oxide, etc. prior to solidifying, thereby to render water glass insoluble. However, these compositions still have a disadvantage that they gradually dissolve when left outdoors for a prolonged time or dipped in hot water or boiling water, although they have water resistance to some degree in water at normal temperature.